Strap clasp

ABSTRACT

The invention relates to a clasp (1) for a band or bracelet (2) having two strips (6, 8) articulated with respect to one another by one of their ends across a common hinge (10), having a cover (3) and a base (9) detachably arranged around a common rod (11), which is guided by a transverse branch (6.4) firmly fixed to the first strip (6), having a first bracelet strand (2.1) fixed to the second strip (8), having a tongue (4) mounted on the base (9) permitting the fixing of a second bracelet strand (2.2), a reinforcement of said fixing taking place by lowering the cover (3) onto the tongue (4) and the lowered cover (3) and base (9) are jointly articulated with respect to the first strip (6), making it possible to open the clasp (1) in order to remove the bracelet (2) without undoing the fixture.

This application claims priority from PCT application numberPCT/CH96/00417 designating the United States, which application ishereby incorporated by reference.

The invention relates to fasteners and more particularly a fastenerhaving a clasp for a bracelet according to the claims.

Fasteners are used in numerous different technical fields. They are e.g.used in security engineering (doors, windows, etc.) and in watch andclock making (wrist-watches). For example, wrist-watch bracelets orbands open and close by means of known fastening means such as anopening out and snap-on clasp.

Such a bracelet clasp is conventionally provided with a bar or pin and astud for fixing strands of the bracelet and is equipped with opening outstrips so as to be able to remove the wrist-watch with the braceletclosed. Said bar permits a permanent fixing of a first strand of thebracelet to the clasp and said lug permits the temporary fixing ofanother strand of the bracelet to the clasp by introducing the stud intoa hole in the said free strand. The bar and the stud are attached todifferent strips, articulated with respect to one another through acommon hinge, permitting an increase in the diameter of the bracelet onseparating and pivoting the two strips so as to be able to remove thebracelet without undoing the temporary fixing of the strand.

Hereinafter, discussion will be limited to the advantages anddisadvantages of a wrist-watch fastener having an opening out andsnap-on clasp. A description will be given of disadvantages associatedwith a stable fixing of the free strand to the stud of a clasp strip, astrong construction of the elements of the clasp and a random lengthregulation of the bracelet in a reliable and easy manner.

The fixing of the free strand is not very reliable when the stud used isarticulated with respect to a support strip and when said mechanism hasmodest dimensions so as to be deformable and damageable under the effectof the torque and tensile forces intercepted by the bracelet. Theopening of the clasp and the regulation of the length of the bracelettake place in several stages and require a large number of elements onthe one hand for carrying out the unlocking of the strips of the claspand on the other for undoing the fixing of the free strand of thebracelet.

A solution permitting an easy fixing of the free strand of the braceletis described in Swiss patent 661,186 by incorporating a stud into asolid cover articulated with respect to a first support strip permittingthe fixing of a free strand by pivoting the cover towards said supportstrip and introducing the stud into a hole in said strand. The lockingof the clasp strips is obtained by notching a second stud placed on thefirst support strip in an opening of a second clasp strip.

This construction suffers from the disadvantage that the torque andtensile forces acting on the bracelet are intercepted by the hinge ofthe cover, so that it can become deformed and damaged, leading to rapidwear.

A solution making it possible to remove the bracelet without any risk ofundoing the fixing of the free bracelet strand is described in Europeanpatent 607,726 with a stud located on a base plate detachably connectedto a first strip, permitting the fixing of the free bracelet strand. Acover is mounted on said first strip and articulated with respect tosaid strip and with respect to said base plate, permitting a pivotingtowards the base plate and a notching with said base plate. Anotherbracelet strand is permanently fixed to a second strip of the clasp. Thelocking of the two strips is obtained by engaging two openings of twostrips on two rods mounted on a third clasp strip.

This construction suffers from the disadvantage that the torque andtensile forces acting on the bracelet are intercepted by the hinge ofthe cover and the base plate, so as to be able to deform and damage it,leading to rapid wear.

Therefore the object of the present invention is to provide a solutionto these problems by creating a fastener having a clasp and with generalapplications, e.g. for a wrist-watch, which has a particularly compactconstruction requiring a minimum number of elements for locking theclasp and regulating the length of the bracelet or band, whilst stillbeing compatible with known, proven manufacturing methods.

This object is achieved by the invention as defined in the claims.

The clasp according to the invention is the result of a detailed studyof mechanisms governing the fixing of bracelet strands and the lockingof clasp strips. The invention more particularly relates to the torqueand tensile forces intercepted by said bracelet or band. Said forces aredirected towards strong, stable elements avoiding any deformation anddamage to the sensitive elements of the clasp, particularly means forlocking the clasp and the cover hinge.

The clasp comprises two strips articulated within one another by one oftheir ends, so that the two strips can be turned down or lowered in oneanother. It is possible to carry out a first locking of the strips bynotching a pin of the inner strip to a transverse branch of the outerstrip.

A bar mounted on the outer strip permits the permanent fixing of a firststrand of the bracelet to the clasp. A tongue mounted on a base permitsthe fixing of another strand or free strand of the bracelet.

The base is mounted in a detachable manner about a rod with respect tothe inner strip. Said rod is installed within a transverse branch of theinner strip. The transverse branch has several aligned half-bushingshaving a guidance function for keeping the rod along their axis. Atleast two half-bushings are spaced from one another, resulting in asmall flapping or stroke angle of the rod and serving as a robust,stable pendant for intercepting the torque and tensile forces actingfrom the bracelet through the tongue to the base and from the base tothe transverse branch and from the transverse branch to the robuststrip, thus preventing the deformation and damage to the more sensitiveelements of the clasp.

The cover is mounted in detachable manner about the rod relative to theinner strip so as to permit a reinforcement of the fixing of the freestrand to the tongue. Advantageously a central portion of the cover islowered or turned down on the tongue.

The cover makes it possible to carry out a second locking of the loweredstrips of the clasp. It is advantageously possible for the lateral armsof the cover and lateral branches of the outer strip to close bynotching.

The cover and base have no direct connection, avoiding any propagationof torque and tensile forces intercepted by the base towards the coverand which could lead to the deformation and damage to the hinge of thecover.

The cover and base of the tongue are jointly articulated with respect tothe inner strip and are individually articulated with respect to oneanother. The said joint articulation of the cover and base takes placeby means of a frictional force of the bracelet connecting the cover andthe base through the bracelet.

Thus, using the clasp according to the invention, it is possible topivot the cover and the base carrying the tongue jointly with respect tothe strips, removing the second locking and giving access to theunlocking of the strips. The fixing of the free strand by the tongueremains reinforced by the cover and is not affected by said jointpivoting, permitting the unlocking of the strips so as to remove thebracelet without any risk of it becoming undone. It is also possible toindividually pivot the cover relative to the base carrying the tongue inorder to remove said reinforcement of the fixing of the free strand andgive access to the tongue. The release of the free strand of thebracelet fixed by the tongue takes place in a separate stage, permittinga length regulation of the bracelet in an easy, rapid manner onseparating the free strand from the tongue. It is in particular possibleto regulate the length of the bracelet without removing the braceletfrom the arm.

The invention is described in greater detail hereinafter relative to theattached drawings, wherein show:

FIGS. 1a, 1b & 1c A diagrammatic view showing a preferred embodiment ofa clasp according to the invention.

FIG. 2 A perspective, exploded view of said preferred embodiment of aclasp according to FIGS. 1a, 1b and 1c.

FIG. 3 A diagrammatic view of the preferred embodiment of a claspaccording to FIGS. 1a, 1b, 1c and 2, showing how the torque and tensileforces are intercepted.

FIGS. 1a, 1b and 1c are a diagrammatic view showing the fixing ofstrands of a bracelet or band to a preferred embodiment of a claspaccording to the invention, together with the locking mechanism of thestrips of said clasp and the reinforcement mechanism of said fixing andtwo possible locking means. FIG. 2 is a perspective, exploded view ofsaid preferred embodiment of a clasp according to FIGS. 1a, 1b and 1c.

The clasp 1 comprises two strips 6, 8 articulated with respect to oneanother by one of their ends through a common hinge 10, so as to be ableto pivot. According to FIG. 2, said ends of the two strips 6, 8 havealigned holes serving as a guide bushing in order to maintain alongtheir axis a rod 10' of the hinge 10. The bracelet and visible elementsof the fastener of the clasp are preferably made from metal, e.g.stainless steel and/or gold.

A first or inner strip 6 is located within a second or outer strip 8.The outer strip 8 has a notch 8.1 with a shape and dimensionscorresponding to those of the inner strip 6, so that the latter ispartly or wholly included in said notch 8.1, when the clasp is in theclosed position. The two longitudinal branches 8.2, 8.3 of the outerstrip 8 have bearing surfaces 8.20, 8.30 for supporting thecorresponding surfaces of the inner strip 6 during the closing of theclasp. It is possible to bring about a first locking of the strips bynotching a pin 6.5 of the inner strip 6 to a transverse branch 8.4 ofthe outer strip 8. As the two strips 6, 8 directly intercept the torqueand tensile forces acting on the bracelet 2, said reciprocal engagementin one another of the two strips 6, 8 leads to a clasp 1 closed in aparticularly reliable manner as a result of its stability and rigidity.

A bar 5, 5' mounted on the outer strip 8 permits the permanent fixing ofa first strand 2.1 of the bracelet 2 to the clasp 1. It is formed by twodetachable, lateral portions 5, 5', which can e.g. be separately screwedinto tapped holes of a central portion 50, firmly attached to atransverse branch 8.4 of the outer strip 8. Said bar 5, 5' permits aparticularly easy and rapid fitting of the first bracelet strand 2.1 byfixing said first strand 2.1 with the aid of a slot 2.10 to the centralportion 50 and by screwing the two lateral portions 5, 5' through saidfirst strand 2.1 in tapped holes of a central portion 50. With theknowledge of the present invention the expert can implement other barconstructions using other means and methods for connecting the lateraland central portions and the first strand to a strip of the clasp.

The tongue 4 mounted on the inner strip 6 permits the fixing of anotherfree strand 2.2 of the bracelet 2. It is fitted to a base 9 attached tothe transverse branch 6.4 of the inner strip 6. The tongue 4 and base 9are fixed, preferably by welding, screwing or even milling in one piece.The transverse branch 6.4 and inner strip 6 are fixed, preferably bywelding. Other connection methods are obviously possible. With theknowledge of the present invention, the expert can implement otherfixing means for other base materials, e.g. heat fusion forheat-fusible, synthetic materials, etc.

The bar 5, 5' and tongue 4 are fitted on the other ends of the twostrips 6, 8, i.e. on the side opposite to the hinge 10. The bar 5, 5'and tongue 4 are fixed to the two strips 6, 8 through a central portion50 and a base 9. These portions 50, 9 intercept the torque and tensileforces exerted on the bracelet 2 and acting through the strands 2.1, 2.2of said bracelet 2 on the bar 5, 5' and tongue 4 of the clasp 1. Theseportions 50, 9 have a solid construction with a certain thickness andrigidity.

The cover 3 and base 9 of the tongue 4 are pivotably mounted andattached to the same transverse branch 6.4 of the inner strip 6. A rod11 is installed within the transverse branch 6.4 of the inner strip 6.Preferably, the transverse branch 6.4 has at least two half-bushings6.4', 6.4", which are aligned with one another and serving as a guidebushing in order to maintain said rod 11 along their axis. The twohalf-bushings 6.4', 6.4" are spaced from one another, so that it ispossible to reduce the stroke clearance of the rod 11. Thus, thehalf-bushings 6.4', 6.4" serve as a pendant for the rod 11 of the base9, which makes it possible to intercept the torque and tensile forcesexerted by the bracelet strand 2.2 on the tongue 4 and then from thebase 9 on rod 11 without deforming and damaging other more sensitiveelements of the clasp 1. This protection of the sensitive elements moreparticularly relates to the locking means of the clasp and the hinge ofthe cover 3. For this purpose, the at least two half-bushings 6.4', 6.4"are arranged so as to prevent any propagation of forces intercepted bythe base 9 towards the cover 3. The base 9 is attached to a centralportion of the rod 11 and is arranged so as to be located between thetwo half-bushings 6.4', 6.4" enabling the base 9 to transmit theintercepted forces to the rod 11 whilst producing a minimum moment. Thecover 3 is attached across two lateral arms 3.2, 3.3 to the ends of therod 11, the cover 3 and base 9 being separated by the two half-bushings6.4', 6.4" enabling the base 9 to transmit the intercepted forces to therod 11, whilst avoiding any deterioration of the cover 3. The resilience(deformation) curve of the rod 11 is limited in such a way by the twohalf-bushings 6.4', 6.4", that there is no danger of deformation anddamage. The construction according to the invention is shown in detailin FIG. 3. Any torque and tensile force F acting on the rod 11 isintercepted by the half-bushings 6.4', 6.4", so that no components ofsaid forces act across the rod 11 on the cover 3. Unlike in the case ofthe clasp described in European patent 607,726, the rod rests in twohalf-bushings, which are spaced from one another and serve as a stableguide bushing. The transmission of torque and tensile forces interceptedby the tongue through the rod to the cover is impossible, the coverbeing separated from the lines of forces intercepted by the bracelet.According to European patent 607,726, said forces intercepted by thebracelet act on the rod and under the effect of the resilience curve ofsaid rod act directly on the relatively sensitive hinge of the cover.

The cover 3 and base 9 are not directly linked. As the base 9 is locatedwithin the cover 3 and within a notch 6.1 of the inner strip 6, it isfitted between the two half-bushings 6.4', 6.4". The two half-bushings6.4', 6.4" are located on the edges of the inner strip 6. The base 9 isattached to a central portion of the rod 11 and between the twohalf-bushings 6.4', 6.4", permitting pivoting by a random angle C. Thecover 3 is installed outside the two half-bushings 6.4', 6.4". The cover3 is attached across two lateral arms 3.2, 3.3 to the ends of said rod11, permitting a pivoting by an angle C. Unlike in the case of the claspdescribed in European patent 607,726, where the cover and base plate areconnected by notching, the cover has no direct, fixed connection to thebase, separating the cover from the lines of forces intercepted by thebracelet, so that said torque and tensile forces cannot damage the hingeof the cover.

Advantageously, the cover 3 and base 9 can carry out a joint pivotingunder the effect of a frictional force transmitted by the bracelet 2.During such a joint pivoting, the cover 3 and base 9 do not change theirreciprocal position, permitting the opening and closing of the bracelet2 without any risk of undoing the fixing of the free strand 2.2 by thetongue 5. Within the scope of the present invention, numerous variantsof such a joint pivoting are possible. For example, as the free strand2.2 has a certain rigidity and is fixed by the tongue 5, it exerts aslight frictional force on the inner walls of the cover 3. A similarfrictional force can be produced by pressing the cover 3 against thefree strand 2.2 during the opening of the cover. Unlike in the case ofthe clasp described in European patent 607,726, joint pivoting isperformed without requiring a direct connection between a cover and abase plate. Said clasp comprises a cover and a base fixed by notching.Such a fixed connection by notching the cover with the base represents acomplication requiring additional elements. The solution according tothe invention fulfills the same function and simplifies the design andconstruction of the clasp. With the knowledge of the present invention,the expert can implement other variants of such a joint pivoting, usingother means and procedures.

The cover 3 is able to control, i.e. release or prevent access to thetongue 4 by pivoting with respect to the base 9. The cover 3 is alsoable to control, i.e. release or prevent the unlocking of the strips 6,8 by pivoting with respect to the closed strips 6, 8. Advantageously,the cover 3 and base 9 pivot jointly in order to effect a secondunlocking and/or for freeing access on first unlocking the strips 6, 8.

In order to open the closed clasp, it is merely necessary to e.g. placea nail on the nail groove 3.1 and lift the cover 3. Advantageously, thecover 3 and base 9 perform a joint pivoting. Under the effect of anopening force, the cover 3 is raised and the elastic, lateral arms 3.2,3.3 of the cover 3 reassume their initial structure and lose the slightdeformation during the engagement on the outer strip 8.

In order to separate the cover 3 from the base 9, it is merely necessaryto continue the pivoting by a random angle C. It is e.g. possible tolimit the pivoting of the base 9 to a smaller angle compared with thecover 3. This separation angle can be fixed at 30° or 40°.

It is consequently possible to regulate the length of the bracelet 2.With reference to FIGS. 1a, 1b and 2 showing a clasp 1 with a raisedcover 3 separated from the base 9, the second bracelet strand 2.2 can beinserted in a space 7 defined on one side by two rods 11, 12 of thecover 3, respectively by a transverse branch 6.4 of the first strip 6,and on the other side by a central portion of said cover 3. Said second,inserted bracelet strand 2.2 is guided by the two rods 11, 12 in thespace 7 permitting a controlled fixing and a random adjustment of thelength of the free strand 2.2 by positive engagement of said free strand2.2 with the tongue 4. Preferably, the second bracelet strand 2.2 isfixed by the insertion of the tongue 4 in one of the holes of the freestrand 2.2, thus preventing a longitudinal movement of the bracelet 2.The tongue 4 has a cambered end so as to be able to maintain the freestrand 2.2 by friction. Advantageously, a central portion of the cover 3can rest on said cambered end of the tongue 4.

In order to again close the open clasp 1, it is sufficient to lower thecover 3 onto the tongue 4 and push the cover 3 and base 9 in thedirection of the two strips 6, 8 until one or both notching systemsengage. It is possible to perform a first locking of the strips by thenotching of a pin 6.5 of the inner strip 6 to a transverse branch 8.4 ofthe outer strip 8.

It is possible to perform a second locking of the strips 6, 8 bynotching lateral arms 3.2, 3.3 of cover 3 with outer portions of the twolongitudinal branches 8.2, 8.3 of the outer strip 8. Under the effect ofa locking force, the lateral arms 3.2, 3.3 of the cover 3 are pushedonto the longitudinal branches 8.2, 8.3 of the outer strip 8. Thelateral branches 3.2, 3.3 have a certain elasticity. The reciprocalspacing of the two longitudinal branches 8.2, 8.3 is chosen in such away that the lateral branches 3.2, 3.3 are slightly deformed duringengagement.

It is obvious that the first locking performed by the pin 6.5 of theinner strip 6 and the transverse branch of the outer strip 8 and thesecond locking performed by the cover 3 of the inner strip 6 and thelongitudinal branches 8.2, 8.3 of the outer strip 8 are optional. Withthe knowledge of the present invention, the expert can implementvariants of a clasp according to the invention closing either solely bysaid first locking or solely by said second locking, or by a combinationof the first and second locking.

We claim:
 1. Clasp (1) for bracelet (2), comprising a first and a secondstrips (6, 8) articulated with respect to one another making it possibleto increase the diameter of the bracelet (2) in order to remove it, afirst bracelet strand (2.1) fixed to a second strip (8) and a second,free bracelet strand (2.2), characterized in that a tongue (4) formingpart of a base (9) permits a fixing of the second bracelet strand (2.2)by positive engagement with the tongue, that the base (9) is detachableabout a rod (11) and that a transverse branch (6.4) is firmly fixed tothe first strip (6) having at least two half-bushings (6.4', 6.4")serving as a guide for the rod (11), making it possible to intercept thetorque and tensile forces exerted by the second bracelet strand (2.2) onthe tongue (4), from base (9) on rod (11) and from rod (11) on the firststrip (6) without deforming and damaging other more sensitive elementsof the clasp (1).
 2. Clasp (1) according to claim 1, characterized inthat the base (9) is attached to a central portion of the rod (11) andbetween two half-bushings (6.4', 6.4") enabling the branch (9) totransmit the intercepted forces to the rod (11) without deforming anddamaging the latter.
 3. Clasp (1) according to claim 1, characterized inthat a cover (3) is attached across the two lateral arms (3.2, 3.3) tothe ends of the rod (11), that the base (9) is attached to a centralportion of the rod (11) and that the cover (3) and base (9) areseparated by two half-bushings (6.4', 6.4"), enabling the base (9) totransmit the intercepted forces to the rod (11) and prevent themaffecting the cover (3).
 4. Clasp (1) according to claim 3,characterized in that the lowered cover (3) and base (9) areinterconnected under the effect of a frictional force across thebracelet strand (2.2), permitting their joint articulation with respectto the first strip (6) and the opening of the clasp (1) in order toremove the bracelet (2) without undoing the fixture.
 5. Clasp (1)according to claim 3, characterized in that the second bracelet strand(2.2) can be inserted in a space (7) defined by two rods (11, 12) of thecover (3) and by the transverse branch (6.4) and that said second,inserted bracelet strand (2.2) is guided in the space (7) permitting acontrolled fixing of the second bracelet strand (2.2) by the tongue (4).6. Clasp (1) according to claim 1, characterized in that a cover (3) isdetachable about the rod (11), permitting the reinforcement of thefixing of the second bracelet strand (2.2) by positive engagement withthe tongue on lowering onto said tongue (4).
 7. Clasp (1) according toclaim 6, characterized in that the tongue (4) has a cambered end so asto be able to hold the free strand (2.2) by friction and that a centralportion of the cover (3) rests on said cambered end of the tongue (4).8. Clasp (1) according to claim 1, characterized in that a pin (6.5) isplaced on the first strip (6) and a transverse branch (8.4) is placed onthe second strip (8), permitting a first locking of the strips (6, 8) bynotching bending the first strip (6) onto the second strip (8).
 9. Clasp(1) according to claim 8, characterized in that it is closed by thefirst locking and/or by the second locking.
 10. Clasp (1) according toclaim 1, characterized in that the first strip (6) is fitted within thesecond strip (8) as a notch (8.1) with a shape and dimensionscorresponding to those of the first strip (6), so that the latter iswholly or partly included in said notch (8.1) when the clasp (1) is inthe closed position.
 11. Clasp (1) according to claim 1, characterizedin that the second strip (8) has two longitudinal branches (8.2, 8.3)with bearing surfaces (8.20, 8.30) for supporting the correspondingsurfaces of the inner strip (6) during the closing of the clasp,rendering the latter rigid and stable.
 12. Clasp (1) according to claim1, characterized in that a bar (5, 5') is mounted on a central portion(50) firmly fixed to one end of the second strip (8), anchoring thefirst bracelet strand (2.1) to the second strip (8), so that the torqueand tensile forces intercepted by the bracelet (2) act across the bar(5, 5') on the central portion (5) and on the second strip (8). 13.Clasp (1) according to claim 12, characterized in that the bar (5, 5')comprises two detachable, lateral portions (5, 5'), which can beseparately screwed into tapped holes of the central portion (50), firmlyattached to a transverse branch (8.4) of the second strip (8),permitting a particularly easy and rapid fitting of the first braceletstrand (2.1) by fixing it with the aid of a slot (2.10) to the centralportion (50) and by screwing the two lateral portions (5, 5') acrosssaid first strand (2.1) in tapped holes of a central portion (50). 14.Clasp (1) according to claim 1, characterized in that the cover (3) haslateral arms (3.2, 3.3), permitting a second locking of the strips (6,8) by notching lateral arms (3.2, 3.3) with outer portions of twolongitudinal branches (8.2, 8.3) of the outer strip (8).
 15. Clasp (1)according to claim 14, characterized in that the lateral arms (3.2, 3.3)have a certain elasticity and the reciprocal spacing of the twolongitudinal branches (8.2, 8.3) is chosen in such a way that thelateral arms (3.2, 3.3) are slightly defined during the engagement ofthe cover (3) on the outer strip (8).
 16. Clasp (1) according to claim14, characterized in that it is closed by the first locking and/or bythe second locking.